Method for using electrocoagulation in hydraulic fracturing

Abstract

A method of improving natural gas release from a well via an enhanced hydraulic fracturing operation. The method includes capturing or retrieving the flow back from the well following the fracturing operation. The flow back or other source water is introduced to an electrocoagulation (“EC”) treatment process. EC treatment separates the water from other fracturing fluid components in the flow back and also removes bacteria and other contaminants. Thereafter, the EC-treated fluid is recycled for subsequent fracturing operations. The process may also be used to treat all source water, including fresh water delivered to the well before it is used as a fracturing fluid.

1. A method of releasing natural gas from a well during a hydraulic fracturing operation, comprising the steps of:
 introducing a hydraulic fracturing fluid into a subterranean formation, the hydraulic fracturing fluid including a mixture of water and fracturing components; 
 capturing at least a portion of the hydraulic fracturing fluid from the subterranean formation; 
 introducing the captured hydraulic fracturing fluid to an electro coagulation (“EC”) treatment process and using the EC treatment process to separate the water from other fracturing fluid components; 
 recycling the water separated via use of the EC treatment process into hydraulic fracturing fluid that is used in subsequent hydraulic fracturing operations, including using the EC treatment process to reduce the viscosity of the hydraulic fracturing fluid that is introduced into the subterranean formation, and wherein the EC treatment process further includes: 
 providing a variable power supply that outputs an alternating current (“AC”); 
 using a variable step down transformer to prevent current spikes in the AC output provided by the variable power supply; 
 rectifying the output of the variable step down transformer from AC to direct current (“DC”); and 
 delivering the rectified DC current to at least one EC treatment cell, for use in inducing electrocoagulation of the captured hydraulic fluid. 
 
     
     
       2. The method of  claim 1 , including varying the output of the variable step down transformer based on the ratio of AC to DC current after rectification. 
     
     
       3. The method of  claim 2 , wherein introducing the captured hydraulic fracturing fluid to an EC treatment process includes:
 exposing the captured hydraulic fracturing fluid to a DC current in at least one EC treatment cell and periodically reversing polarity of the DC current in the EC treatment cell during the EC treatment process. 
 
     
     
       4. The method of  claim 3 , further including adjusting the pH of the captured hydraulic fracturing fluid during the EC treatment process to facilitate effluent flocculation. 
     
     
       5. The method of  claim 1 , wherein introducing the captured hydraulic fracturing fluid to an EC treatment process includes:
 using the EC treatment process to remove bacteria in the water separated from the flow back before recycling the water in subsequent hydraulic fracturing operations. 
 
     
     
       6. The method of  claim 5 , using the EC treatment process to reduce turbidity in the water separated from the flow back before recycling the water in subsequent hydraulic fracturing operations. 
     
     
       7. A method of releasing natural gas from a well during a hydraulic fracturing operation, comprising the steps of:
 introducing a hydraulic fracturing fluid into a subterranean formation at a well head site, the hydraulic fracturing fluid including a mixture of water and fracturing components; 
 retrieving flow-back fluid at the well head resulting from the hydraulic fracturing operation; 
 treating the flow-back fluid using an electrocoagulation (“EC”) treatment process to separate water in the flow-back fluid from other fracturing components, wherein the EC treatment process occurs at the well head site; 
 using the EC treatment process to reduce viscosity of the hydraulic fracturing fluid that is introduced into the subterranean formation; 
 storing the treated water at the well head site; 
 recycling the stored treated water as a hydraulic fracturing fluid used in subsequent hydraulic fracturing operation; and wherein the EC treatment process includes: 
 providing a variable power supply that outputs an alternating current (“AC”); 
 using a variable step down transformer to prevent current spikes in the AC output provided by the variable power supply; 
 rectifying the output of the variable step down transformer from AC to direct current (“DC”); and 
 delivering the rectified DC current to at least one EC treatment cell, for use in inducing electrocoagulation of the captured hydraulic fluid. 
 
     
     
       8. The method of  claim 7 , wherein introducing the captured hydraulic fracturing fluid to an EC treatment process includes:
 using the EC treatment process to remove bacteria in the water separated from the flow back before recycling the water in subsequent hydraulic fracturing operations. 
 
     
     
       9. The method of  claim 7 , including using the EC treatment process to reduce turbidity in the water separated from the flow back before recycling the water in subsequent hydraulic fracturing operations. 
     
     
       10. The method of  claim 7 , including varying the output of the variable step down transformer based on the ratio of AC to DC current after rectification. 
     
     
       11. The method of  claim 10 , wherein introducing the captured hydraulic fracturing fluid to an EC treatment process includes:
 exposing the captured hydraulic fracturing fluid to a DC current in at least one EC treatment cell and periodically reversing polarity of the DC current during the EC treatment process.